In case you need a permanent and instantaneous answer then do observe the given steps to fix canon printer offline issue:
Connecting printer with Mac: Check if you have properly linked your printer with the Mac or now not. Check if there is any wire that is loose or broken. If you located any then trade them right away.
Check all of the wires: Are you sure that every one the USBs are inserted into the ports? Remove all of the wires from the again of the printer and join them again. Check if Canon printer is offline mac issue got solved or now not.
Wireless connectivity: After checking all of the wires if well connected or no longer. Now, test for the wireless connectivity. The first actual element that you have to do is to restart your router and your mac. Now, open the Mac and choose the “default printer” through the “device desire” in settings.